A secondary battery is used as a power source for various devices ranging from mobile devices to electric vehicles or hybrid vehicles due to its repetitive charge and discharge capability. In addition, new battery models that are capable of generating stronger power while being physically compact are being continuously developed as technologies in the field advance.
A secondary battery module that is applied to electric vehicles or hybrid vehicles is a battery that is modulized by being electrically connected with a plurality of battery cells. Such a module is called medium and large sized battery pack and is used due to the necessity of high energy storage capacity. The medium and large sized battery pack is configured such that a plurality of battery cells are received in a casing by being layering and is electrically connected.
In particular, the casing is provided with a voltage sensing module that detects and controls voltage, current, and temperature of the battery cells so as to prevent a fire or an explosion caused by overcharge, overdischarge, overcurrent, heating, and a series of side reactions of the battery cells.
The battery pack is a combination of a plurality of the battery cells, so in the case that some of the battery cells are overvoltaged, overcurrented, or overheated, safety and operational efficiency is not guaranteed. Thus, the voltage sensing module is provided so as to detect and control voltage, current, and temperature of the battery cells.
FIG. 1 is a view illustrating a battery device 11 that is provided with a conventional voltage sensing module 15.
As shown in FIG. 1, a voltage sensing module 15 is connected to cell tabs 13a of a plurality of layered battery cells 13. The voltage sensing module 15 is electrically connected with respective cell tabs 13a of the battery cells 13 via bus bars 19, thereby detecting output voltage and current of respective battery cells 13.
The conventional voltage sensing module 15 includes: an insulating body 17; a control substrate 21 mounted to the body 17; and a plurality of bus bars 19 being connected to the cell tabs 13a in a state where the bus bars 19 are fixedly mounted to the body 17, wherein an end of respective bus bars 19 is soldered to a control circuit of the substrate 21. The bus bars 19 convey output voltage of the battery cells 13 to the substrate 21 so as to allow the control circuit provided in the substrate 21 to take appropriate control.
Reference numeral 23 refers to a soldering area where the bus bars 19 are soldered to the substrate 21. In other words, bus bars 19 are soldered to the control circuit of the substrate 21.
However, the conventional voltage sensing module 15 is problematic in that the bus bars 19 are soldered to the substrate 21, whereby the assembly process of the voltage sensing module 15 is inconvenient.
To be more specific, the bus bars are heated and soldered to the substrate in a state where a first end of the associated one of the bus bars 19 is inserted into a slit formed on the substrate 21, and thus the soldering process is inconvenient. In particular, in the case of bad welding, it is possible to damage a pattern of the control circuit and to short-circuit the control circuit.
In addition, the bus bars 19 are soldered to the substrate 21, whereby it is impossible to replace only the substrate 21 when the substrate 21 has a problem. For example, when a pattern of the substrate 21 is damaged or a component, such as a fuse, is broken, it is impossible to disassemble the substrate 21 from the battery device. Thus, the battery device 11 or the whole battery pack should be replaced due to a problem of the substrate. This kind of problem frequently occurs in the case of electric vehicles or hybrid vehicles that endure shaking and shocks due to driving.